Contact assembly



Feb. 3, 1959 E. E. WILLS cormc'r ASSEMBLY Filed Oct. so, 1953 IN V ENTOR. [7-0177 1'7. }////5 ATTORNEYS CQNTACT ASSEMBLY Ervin E. Wills,Aifton, Mo., assignor to Electric Products Company, a corporation ofDelaware Application October so, 1953 Serial No. 389,245 8 Claims. or.339-255 The present invention relates to switches and more particularlyto electric contact assemblies of the plug-in type.

Plug-in contact assemblies of the type generally used, for example andnot by way of limitation, in a draw-out switch gear comprise astationary blade-like contact member and a companion movable plug-incontact member. The movable plug-in contact member comprises aconducting part provided, at one end thereof, with a plurality of pairsof contact fingers which engage the stationary blade contacttherebetween. Heretofore, said fingers were fixedly secured to thecontact part and were usually spring biased to provide the requiredcontact pressure, the fingers of each pair being urged apart upon theirengagement with the stationary blade contact. However, corrosion or thepresence of foreign matter at the point of securement for connection ofthe fingers to the conducting part tended to decrease current fiowthrough the movable plug-in contact member.

Therefore, the primary object of the present invention is to eliminatethe causes of the reduced current flow in plug-in contact members of theprior art.

Another object is the provision of a plug-in contact member wherein thecontact fingers are free of fixed s ecurement or connection to theirconducting part.

Another object is the provision in a plug-in contact member of means toprovide a wiping action between the contact fingers and their conductingpart to provide clean contact surfaces.

A further object is the provision of means whereby the aforementionedwiping action may be achieved without necessitating any structuralmodifications to the stationary blade contact.

A further object is the provision of means in a plug-in contact assemblyhaving a conducting part with a plurality of pairs of contact fingers tocause said fingers to move relative to said conducting part to effect awipingaction therewith automatically upon engagement with the stationaryblade contact and further returning said fingers automatically to theiroriginal position during disengagement of said fingers from saidstationary blade contact and insuring that said fingers remain in theproper position for subsequent engagement.

The above and other objects, features and advantages of the presentinvention will be more fully understood from the following descriptionconsidered in connection with the accompanying illustrative drawings.

In the drawings which illustrate the best mode presently contemplated byme of carrying out my invention:

Fig. 1 is a plan view of a plug-in contact assembly pursuant to thepresent invention, the companion movable and stationary contact membersbeing illustrated in the disengaged condition thereof;

Fig. 2 is a section taken on line 2-2 of Fig. i;

Fig. 3 is a section similar to that of Fig. 2 but showing the. companionmovable and stationary contact members just beginning to makeengagement;

Fig. 4 is a section similar to that of Fig. 2 but show:

Patented Feb. 3,

ing the companion movable and stationary contact members engaged totheir fullest extent; and

Fig. 5 is an end view of the movable contact member taken in thedirection of the arrow of Fig. 2.

Referring now to the drawings, reference numeral 30 designates astationary blade-like contact member suitably mounted in position andwhich, as here shown, is formed of any suitable electric conductingmaterial reversely bent upon itself to form an arcuate cam-like edge 12.It will be understood that the stationary bladelike contact 10 could bemade solid if desired. The purpose of the curved edge 12 willhereinafter become apparent. A movable contact assembly designatedgenerally at 14 comprises a conducting port or movable contact member 16which takes the form of a blade-like member which is of approximatelythe same thickness as the distance between the outer surfaces 11 and 13of the contact 16. It will be understood that the contact part in isformed of any suitable electric conducting material and may be carriedby a suitable portion 17 of a draw-out switch gear or similar device,being secured thereto as by the securing elements 19. A frame retainermember or mounting member shown generally at 18 is floatingly mounted onthe conducting part 16 by a pair of shoulder screws 2 having a threadedportion 21 and a shoulder portion 23. To this end the frame member 318is provided with two elongated apextures 22 adapted to receive saidshoulder screws. The conducting part 16 is provided with tapped holes 24in alignment with the openings 22 and which receive the threadedportions 21 of the screws 20. interposed between the frame 38 and theconducting member 16 and surrounding the shoulder portions 23 of thescrews 2i) in a helical coil spring 26 which normally biases the framemember outwardly with respect to the conducting part 16 as shown mostclearly in Figs. 2 and 3. The .frame member 18 is provided with acentral portion 23 in which the openings 22 are disposed and twooppositely disposed portions 30 extending outwardly from said centralportion in angular relation thereto. The frame member 18 is furtherprovided with a peripherally extending flange 32 for increasing therigidity of the frame member, which is preferably formed from relativelythin sheet metal. Each of the angular portions 3% of the frame 18 havetherein a pair of notches or cut-out 1nount ing portions 34 andextending through each of said notches is a pair of contact fingers orbridging contacts referred to generally at 36. The contact fingers eachhave a forward inclined edge 33, a front contact portion 41 and a rearcontact portion 42. The contact fingers are each further provided with anotch 54 disposed in one surface thereof which seats on the edges of thenotches 34 in frame member 18 as best shown in Figs. 2, 3 and 4. On theopposite elongated surfaces of the contact fingers there is provided apair of notches 46 and 48 which serve to position flat leaf spring 5%which is provided for each pair of contact fingers and which urges saidcontact fingers in the direction of conducting part 16.

The operation of my contact assembly will now be described. When thestationary contact 10 and the movable conducting part 16 are disengagedfor opening the switch,

assembly 14 is moved in the direction depicted by the arrow in Fig. 2the inclined forward portions 38 of the contact fingers engagestationary contact in the manner shown in Fig. 3. Further movement inthe direction of the arrow will cause the front contact portions 40 toride or cam over the curved or companion portion 12 of stationarycontact 10. When this occurs it will be obvious that said contactfingers will be spread apart against the action of springs 50, the pointof contact between the rear contact portion 42 and the conducting part16 acting as a fulcrum for the outward pivotal movement that occurs.Since the flat springs 50 are relatively strong as compared to thehelical coil springs 26, the clamping action effected by the frontcontact portions on the parallel outer surfaces 11 and 13 of stationarycontact 1v) is sutficient to maintain said contact fingers momentarilystationary relative to contact 10 even though the conducting part 16 isstill moving in the direction of the arrow. Thus a relative movementbetween contact fingers 36 and the conducting part 16 is achieved whichresults in a wiping action between the rear contact portions 42 and saidconducting part, it being obvious that during said relative movementspring 26 is being compressed. Said relative movement will terminatewhen flange 32 of mernber 18 engages the confronting end of conductingpart 16 as shown clearly in Fig. 4. At this time the contact fingers 36and conducting part 16 again begin to move as a unit during whichmovement front contact portions 46 make a wiping engagement withsurfaces 11 and 13 of stationary contact 10. This movement willterminate when the movable contact assembly 14 has moved inwardly to thepoint where the head of screws abuts the outer edge of contact 10 asshown in Fig. 4. To disengage the movable contact assembly from thestationary contact blade thereby breaking the circuit, it is simplynecessary to move the contact assembly 14 in the opposite direction tothat indicated by the arrows of Figs. 2 and 3 until the assembly againresumes the position 'of first Fig. 3 and then Fig. 2. When theconducting part 16 is moved in its disengaging direction from theposition shown in Fig. 4, the clamping action between front contactportions 40 and the stationary contact 10 will again cause the contactfingers to remain fixed until the heads of the shoulder screws 20,which, of course, are moving with conducting part 16 to which they aresecured, engage the central portion 28 of the frame member 18. When thisoccurs the contact fingers will resume movement with conducting part 16as a unit until complete disengagement occurs. After the contacts arecompletely disengaged, spring 26 will serve to maintain the contactfingers 36 in their forwardly disposed position relative to conductingpart 16 whereby to insure that said fingers will he properly positionedfor subsequent engagement with stationary contact 10.

Since it is important that the contact fingers be properly aligned withrespect to the stationary blade contact 10, the mounting openings 22 forframe member 18 are made elongated. By this construction said framemember can be laterally shifted with respect to conducting part 16 untilproper alignment of said contact fingers with said stationary bladecontact 10 is attained.

The present invention is related to the subject matter of my UnitedStates patent application Serial No. 336,515, filed February 12, 1953,assigned to the assignee of the present application.

It will be obvious that while four pairs of contact fingers have beenillustrated as being carried by conducting part 16, any number of pairsof contacts may be employed. Also, if desired, the various pairs ofcontact fingers can be staggered in the manner indicated in saidapplication, Serial No. 336,515, in order to reduce the force requiredto move the movable contact assembly into engagement with the fixedblade contact.

While I have shown and described the preferred embodiments of myinvention, it will be understood that various changes may be made in theideas or principles of the invention within the scope of the appendedclaims.

Having thus described my invention, what I claim and desire to secure byLetters Patent, is:

1. A contact assembly comprising a pair of relatively movable contactmembers, a frame member carried by one of said contact members andhaving parts thereof extending therefrom at the opposite sides,respectively of said one contact member, said parts each being providedwith a plurality of spaced mounting portions with said portions in eachpart in registry with associated portions, respectively, in the otherpart, a bridging contact mounted in each mounting portion so that thebridging contacts in each pair of associated portions in said parts arein alignment, said bridging contacts projecting forwardly of said onecontact member, and spring means provided in said mounting portions,respectively, for biasing the aligned bridging contacts toward eachother.

2. A contact assembly comprising a pair of relatively movable contactmembers, a frame member carried by one of said contact members andhaving parts thereof extending therefrom at the opposite Sides,respectively of said one contact member, said parts each being providedwith a plurality of spaced mounting portions with said portions in eachpart in registry with associated portions respectively, in the otherpart, a bridging contact mounted in each mounting portion so that thebridging contacts in each pair of associated portions in said parts arein alignment, said bridging contacts projecting forwardly of said onecontact member, and spring means provided in said mounting portions,respectively for biasing the aligned bridging contacts toward eachother, said spring means being constituted by leaf springs and each leafspring extending longitudinally of its associated bridging contact.

3. A contact assembly comprising a stationary contact member and acompanion movable contact member, a frame member mounted by said movablecontact member and having parts thereof extending therefrom at oppositesides, respectively, of said movable contact member, a bridging contactmounted in each of saidparts and extending forwardly of said movablecontact member, said bridging contacts each being recessed in a portionthereof which confronts said movable contact, and said frame parts beingengaged in the recesses of the bridging contacts mounted thereby forpreventing relative longitudinal displacement of said bridging contacts,said frame member mounting a leaf spring for each of said bridgingcontacts, and said leaf springs engaging their associated bridgingcontacts in portions of the latter opposite the recessed portionsthereof for biasing said bridging contacts toward each other.

4. A contact assembly for engaging a companion conducting member, saidassembly including a plurality of elongated bridging contacts, a contactmember carrying saidbridging contacts, said contact member having an endand having lateral surfaces adjoining said end, each of said bridgingcontacts being in wiping engagement with a lateral surface of saidcontact member, said end of said contact member being flanked by saidbridging contacts, the bridging contacts projecting beyond said end forengagement with the companion conducting member, a retainer havinginterlocking engagement with said bridging contacts for retaining themagainst shifting longitudinally in relation to each other, said retainerhaving a portion disposed between said bridging contacts opposite saidend of said contact member, and a lost-motion connecting elementextending from said end of said contact member loosely throughsaid'retainer portion to the opposite side thereof and having anenlargement at said opposite side of said retainer portion, saidenlargement being spaced from said end of said contact member by adistance greater than the thickness of said retainer portion forproviding limited movement of the said bridging contacts as a unit withsaid retainer in relation to said contact member.

5. A contact assembly for engaging a companion conducting member, saidassembly including a plurality of elongated bridging contacts, a contactmember carrying said bridging contacts, said contact member having anend and having lateral surfaces adjoining said end, each of saidbridging contacts being in wiping engagement with a lateral surface ofsaid contact member, said end of said contact member being flanked bysaid bridging contacts, the bridging contacts projecting beyond said endfor engagement with the companion conducting member, a retainer havinginterlocking engagement with said bridging contacts for retaining themagainst shifting longitudinally in relation to each other, said retainerhaving a portion disposed between said bridging contacts opposite saidend of said contact member, a lost-motion connecting element extendingfrom said end of said contact member loosely through said retainerportion to the opposite side thereof and having an enlargement at saidopposite side of said retainer portion, said enlargement being spacedfrom said end of said contact member by a distance greater than thethickness of said retainer portion for providing limited longitudinalmovement of said bridging contacts as a unit with said retainer inrelation to said contact member, and spring biasing means establishing anormal position of said retainer at one end of the motion afforded bysaid lost-motion connecting element when the contact assembly isseparated from the companion conducting member.

6. A contact assembly for engaging a companion conducting member,saidassembly including a plurality of elongated bridging contacts, acontact member carrying said bridging contacts, said contact memberhaving an end and having lateral surfaces adjoining said end, each ofsaid bridging contacts being in wiping engagement with a lateral surfaceof said contact member, said end of said contact member being flanked bysaid bridging contacts, the bridging contacts projecting beyond said endfor engagement with the companion conducting member, a retainer having aportion in interlocking engagement with said bridging contacts forretaining them against shifting longitudinally in relation to eachother, and said retainer having slots receiving said bridging contactsfor retaining them in predetermined spaced relation, said retainerportion being disposed between said bridging contacts opposite said endof said contact member, and a lostmotion connecting element extendingfrom said end of said contact member loosely through a transverselyenlarged passage in said retainer portion to the opposite side thereofand having an enlargement at said opposite side of said retainerportion, said enlargement being spaced from said end of said contactmember by a distance greater than the thickness of said retainerportion, said lost-motion connecting element thereby providing forlimited movement of the said bridging contacts as a unit with saidretainer both longitudinally and transversely of said contact member.

7. A contact assembly for engaging a companion conducting member, saidassembly including a plurality of elongated bridging contacts, a contactmember carrying said bridging contacts, said contact member having anend and having lateral surfaces adjoining said end, each of saidbridging contacts being in wiping engagement with a lateral surface ofsaid contact member, said end of said contact member being flanked bysaid bridging contacts, the bridging contacts projecting beyond said endfor engagement with the companion conducting memher, a retainer having aportion in interlocking engagement with said bridging contacts forretaining them against shifting longitudinally in relation to eachother, and said retainer having slots receiving said bridging contactsfor retaining them in predetermined spaced relation, said retainerportion being disposed between said bridging contacts opposite said endof said contact member, a lost-motion connecting element extending fromsaid end of said contact member loosely through a transversely enlargedpassage in said retainer portion to the opposite side thereof and havingan enlargement at said opposite side of said retainer portion, saidenlargement being spaced from said end of said contact member by adistance greater than the thickness of said retainer portion, saidlost-motion connecting element thereby providing for limited movement ofsaid bridging contacts as a unit with said retainer both longitudinallyand transversely of said contact member, and spring means biasing saidretainer and the bridging contacts as a unit toward the companionconducting member to establish a normal configuration of the lost-motionconnection prior to engagement of the bridging contacts with thecompanion conducting member.

8. A contact assembly for engaging a companion con ducting member, saidassembly including a plurality of elongated bridging contacts, a contactmember carrying said bridging contacts, said contact member having anend and having lateral surfaces adjoining said end, each of saidbridging contacts being in wiping engagement with a lateral surface ofsaid contact member, said end of said contact member being flanked bysaid bridging contacts, the bridging contacts projecting beyond said endfor engagement with the companion conducting memher, a retainer having aportion in interlocking engagement with said bridging contacts forretaining them against shifting longitudinally in relation to eachother, said retainer having slots receiving said bridging contacts forretaining them in predetermined spaced relation, said retainer portionbeing disposed between said bridging contacts opposite said end of saidcontact member, and a pair of laterally spaced lost-motion connectingelements extending from said end of said contact member at one side ofsaid retainer portion loosely through slots in said retainer portion tothe opposite side thereof, the slots being elongated in the directiontransverse to a line through the pair of lost-motion connectingelements, and each said connecting element having an enlargement at saidopposite side of said retainer portion, each said enlargement beingspaced from said end of said contact member by a distance greater thanthe thickness of said retainer portion, said lost motion connectingelements thereby providing limited movement of said bridging contacts asa unit with said retainer both longitudinally of and in one directiontransversely of said contact member.

References Cited in the file of this patent UNITED STATES PATENTS2,243,567 Linde May 27, 1941 2,265,006 Rubel Dec. 2, 1941 2,300,893Hayford Nov. 3, 1942. 2,376,818 Rubel May 22, 1945 2,386,611 Ileman Oct.9, 1945

